Faulty Link Detection Method, Apparatus, Node, and System

ABSTRACT

A faulty link detection method includes receiving statistical data that is reported by all nodes every preset quantity of packets that carry a program clock reference value. All the nodes collect statistical data starting from a unified program clock reference value. The quantity of packets lost between an upstream node and a downstream node among all the nodes is acquired according to the statistical data. A faulty link is determined according to the quantity of packets lost between the upstream node and the downstream node.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2011/081285, filed on Oct. 25, 2011, which claims priority toChinese Patent Application No. 201010601481.3, filed on Dec. 15, 2010,both of which are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to the field of interactive internetprotocol television technologies, and in particular, to a faulty linkdetection method, apparatus, node, and system.

BACKGROUND

IPTV (Internet Protocol Television, interactive internet protocoltelevision) is a technology that provides a home user with a variety ofinteractive services including a digital television by using a broadbandIP network. The IPTV mainly provides a user with a video service, andtherefore has a very high requirement on a transport network. Once thetransport network fails to meet a transport quality requirement of theIPTV, quality degradation phenomena such as mosaic, a pause, and a skipof a video picture occur, which seriously affects QoE (Quality ofExperience) of a terminal user. Therefore, once a problem occurs in thetransport network, an IPTV service operator desires to quickly andtimely locate which link where the problem occurs in the transportnetwork, that is, to implement fault location.

In an existing IPTV network, a network fault is detected through an MDI(Media Delivery Index). Specifically, the MDI includes two measurementindicators, namely, a DF (Delay Factor) and an MLR (Media Loss Rate). ADF value indicates delay and jitter conditions of a tested video stream,and an MLR value indicates a packet loss rate in transmission of thetested video stream. After obtaining a DF value and an MLR value, eachmonitoring node sends, according to its own timing mechanism, the testvalue to a management center periodically; and by respectively comparingDF values and MLR values reported by different nodes periodically, themanagement center can obtain that a jitter occurs between which devicesand a packet loss occurs between which devices. For example, upstreamand downstream values are DF1 and MLR1, and DF2 and MLR2 respectively.If DF1=5 ms, MLR1=0; DF2=40 ms, and MLR2=5, it indicates that a jitter(DF) of video on an upstream device is small but a jitter (DF) on adownstream device is quite large, and it indicates that a jitter occursbetween the two devices. Ideal IP video stream transmission requiresthat an MLR value should be zero. Because the MLR1 of the upstreamdevice is equal to 0, it indicates that there is no packet loss in thisperiod, while because the MLR2 of the downstream device is equal to 5,it indicates that a packet loss (5 TSs (Transport Stream) per second)occurs on the downstream device in this period, and a link between theupstream node and the downstream node is a faulty link.

SUMMARY OF THE INVENTION

After analyzing the prior art, the inventor finds the prior art has atleast the following defects. A DF value is a value in the statisticalsense, and calculation is based on an MR (Media Ratio, code rate of amedia stream) and a number difference between bytes received in acurrent measurement time period. The DF value only reflects a change ofa code rate of a media stream, and cannot accurately weigh whether apause or skip occurs in a current video picture of a terminal decoder.Furthermore, the DF value loses its reference value for a variable bitrate of a media stream. Secondly, calculation of an MLR requires a TS CC(Transport Stream Continuity Counter), but the CC has only 4 bits and arepetition period is too short. Therefore an actual media loss ratecannot be calculated accurately. Moreover, clocks of nodes may not besynchronous, and even though the clocks are synchronous, start pointsfor detecting a video stream as well as timing mechanisms for reportingof the nodes may also be inconsistent. Due to the foregoing problems, amanagement center cannot perform accurate comparison between upstreamand downstream nodes according to a reported calculation result ofdetection, and therefore it is difficult to accurately solve a problemof fault location as desired by the operator.

To find a faulty link more accurately, embodiments of the presentdisclosure provide a faulty link detection method, apparatus, node, andsystem. The technical solutions are as follows.

In one aspect, a faulty link detection method is provided, where themethod includes receiving statistical data that is reported by all nodesevery preset quantity of packets that carry a program clock referencevalue, where all the nodes collect statistical data starting from aunified program clock reference value, and the statistical data includesa start program clock reference value and an end program clock referencevalue, and the quantity of packets received at the start program clockreference value and the quantity of packets received at the end programclock reference value acquiring, according to the statistical data, thequantity of packets lost between an upstream node and a downstream nodeamong all the nodes, and determining a faulty link according to thequantity of packets lost between the upstream node and the downstreamnode.

In one aspect, a faulty link detection apparatus is provided, where theapparatus includes a receiving module, configured to receive statisticaldata that is reported by all nodes every preset quantity of packets thatcarry a program clock reference value, where all the nodes collectstatistical data starting from a unified program clock reference value,and the statistical data includes a start program clock reference valueand an end program clock reference value, and the quantity of packetsreceived at the start program clock reference value and the quantity ofpackets received at the end program clock reference value, an acquiringmodule, configured to acquire, according to the statistical data, thequantity of packets lost between an upstream node and a downstream nodeamong all the nodes, and a determining module, configured to determine afaulty link according to the quantity of packets lost between theupstream node and the downstream node.

In another aspect, a node is provided, where the node includes a firstreceiving module, configured to receive an enabling instructiondelivered by a link fault detection apparatus, and acquire a currentprogram clock reference value a statistics module, configured to collectstatistical data starting from the current program clock referencevalue, and a sending module, configured to send the statistical data tothe link fault detection apparatus every preset quantity of packets thatcarry a program clock reference value, so that the link fault detectionapparatus analyzes the statistical data to determine a faulty link,where the statistical data includes a start program clock referencevalue and an end program clock reference value, and the quantity ofpackets received at the start program clock reference value and thequantity of packets received at the end program clock reference value.

In another aspect, a faulty link detection system is further provided,where the system includes a link fault detection apparatus, configuredto receive statistical data that is reported by all nodes every presetquantity of packets that carry a program clock reference value, whereall the nodes collect statistical data starting from a unified programclock reference value, and the statistical data includes a start programclock reference value and an end program clock reference value, and thequantity of packets received at the start program clock reference valueand the quantity of packets received at the end program clock referencevalue; acquire, according to the statistical data, the quantity ofpackets lost between an upstream node and a downstream node among allthe nodes; and determine a faulty link according to the quantity ofpackets lost between the upstream node and the downstream node, and anode, configured to receive an enabling instruction delivered by thelink fault detection apparatus and acquire a current program clockreference value; collect statistical data starting from the currentprogram clock reference value; and send the statistical data to the linkfault detection apparatus every preset quantity of packets that carry aprogram clock reference value, so that the link fault detectionapparatus analyzes the statistical data to determine the faulty link.

In the technical solutions provided in the embodiments of the presentdisclosure, statistical data collected at a unified reference time bydifferent network nodes is acquired, and the accurate quantity ofpackets lost between an upstream node and a downstream node is obtainedthrough comparison, so as to determine a faulty link, therebyeffectively ensuring that an IPTV service operator locates a networkfault quickly and effectively.

BRIEF DESCRIPTION OF THE DRAWINGS

To illustrate the technical solutions in the embodiments of the presentdisclosure or in the prior art more clearly, the accompanying drawingsrequired for describing the embodiments or the prior art are brieflydescribed in the following. Apparently, the accompanying drawings in thefollowing description merely show some embodiments of the presentdisclosure, and persons of ordinary skill in the art may still deriveother drawings from these accompanying drawings without creativeefforts.

FIG. 1 is a flowchart of a faulty link detection method provided inEmbodiment 1 of the present disclosure;

FIG. 2 is a flowchart of a faulty link detection method provided inEmbodiment 2 of the present disclosure;

FIG. 3 is a schematic diagram of information interaction between nodesand a management center provided in Embodiment 2 of the presentdisclosure;

FIG. 4 is a schematic diagram of a faulty link detection apparatusprovided in Embodiment 3 of the present disclosure;

FIG. 5 is a schematic diagram of another faulty link detection apparatusprovided in Embodiment 3 of the present disclosure;

FIG. 6 is a schematic diagram of a node provided in Embodiment 3 of thepresent disclosure;

FIG. 7 is a schematic diagram of another node provided in Embodiment 3of the present disclosure; and

FIG. 8 is a schematic diagram of a faulty link detection system providedin Embodiment 3 of the present disclosure.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

To make the objectives, technical solutions, and advantages of thepresent disclosure more comprehensible, the embodiments of the presentdisclosure are described in further detail in the following withreference to the accompanying drawings.

Before a faulty link detection method provided in the present disclosureis described, basic knowledge of the present disclosure is describedbriefly first.

PCR (Program Clock Reference) is a synchronization clock of a receivingend and a transmitting end, where the synchronization clock isestablished by a real-time transmission system to ensure normal workingof the receiving end and the transmitting end and consistency offrequencies and phases of the receiving end and the transmitting end.Specifically, at the transmitting end, a counter is used to count asystem to form a PCR value, and then the PCR value is transferredtogether with data to the receiving end at a regular time interval. Thereceiving end has a local working clock whose rated frequency is thesame as that of a clock at the transmitting end, and also has a counterwhich counts the local clock at the receiving end to form a local clockreference. In this case, the transmitting end extracts the PCR from atransport stream, inserts the PCR as well as coding information of anaudio frame and a video frame into a PES (Packetised Elementary Streams)packet, the receiving end puts PCR values that are in the audio frameand the video frame in a buffer and waits for values in audio and videoof the transmitting end for comparison, and then controls avoltage-controlled oscillator (VCXO) by using a comparison result.Frequencies of the receiving end and transmitting end are phase-lockedthrough adjustment, so as to implement complete synchronization of soundand images at the receiving end and the transmitting end.

FIG. 1 illustrates a first embodiment (Embodiment 1) of the presentdisclosure that provides a faulty link detection method. The methodincludes the following steps.

Step 101: Receive statistical data that is reported by all nodes everypreset quantity of packets that carry a program clock reference value.

All the nodes collect statistical data starting from a unified programclock reference value. The statistical data includes a start programclock reference value and an end program clock reference value, and thequantity of packets received at the start program clock reference valueand the quantity of packets received at the end program clock referencevalue.

Step 102: Acquire, according to the statistical data, the quantity ofpackets lost between an upstream node and a downstream node among allthe nodes.

Step 103: Determine a faulty link according to the quantity of packetslost between the upstream node and the downstream node.

The acquiring, according to the statistical data, the quantity ofpackets lost between the upstream node and the downstream node among allthe nodes includes calculating, according to the quantity of packetsreceived at the start program clock reference value and the quantity ofpackets received at the end program clock reference value, thequantities of packets that are received by all the nodes between thesame start program clock reference value and the same end program clockreference value, and calculating, according to the quantities of packetsthat are received by all the nodes between the same start program clockreference value and the same end program clock reference value, thequantity of packets lost between the upstream node and the downstreamnode among all the nodes.

In this embodiment, the determining the faulty link according to thequantity of packets lost between the upstream node and the downstreamnode includes determining whether the quantity of packets lost betweenthe upstream node and the downstream node among all the nodes is zero,and if the quantity is not zero, determining that a link between theupstream node and the downstream node is the faulty link.

Further, in this embodiment, before the calculating the quantities ofpackets that are received by all the nodes between the same startprogram clock reference value and the same end program clock referencevalue, the method further includes determining whether end program clockreference values reported by all the nodes are consistent, if the endprogram clock reference values are consistent, continuing to perform thestep of calculating the quantities of packets that are received by allthe nodes between the same start program clock reference value and thesame end program clock reference value, and if the end program clockreference values are inconsistent, correcting an end program clockreference value of a node until the end program clock reference valuesreported by all the nodes are consistent, where the end program clockreference value of the node is inconsistent with end program clockreference values of other nodes, and continuing to perform the step ofcalculating the quantities of packets that are received by all the nodesbetween the same start program clock reference value and the same endprogram clock reference value.

In this embodiment, the correcting the end program clock reference valueof the node, where the end program clock reference value of the node isinconsistent with the end program clock reference values of the othernodes, includes sending a correction message to a node whose end programclock reference value is inconsistent with those of the other nodes, sothat the node whose end program clock reference value is inconsistentwith those of the other nodes modifies the quantity of packets thatcarry a program clock reference value, where the quantity of packetsthat carry a program clock reference value is used as its own interval,and collects statistical data at an interval of the modified quantity ofprogram clock reference values.

An execution subject in this embodiment is a faulty link detectionapparatus, where the faulty link detection apparatus may be a managementcenter, which is not specifically limited in this embodiment.

In the technical solution provided in the embodiment of the presentdisclosure, statistical data collected at a unified reference time bydifferent network nodes is acquired, and the accurate quantity of IPpackets lost between an upstream node and a downstream node is obtainedthrough comparison, so as to determine a faulty link, therebyeffectively ensuring that an IPTV service operator locates a networkfault quickly and effectively.

FIG. 2 illustrates a second embodiment (Embodiment 2) of the presentdisclosure that provides a faulty link detection method. The methodincludes the following steps. The embodiment will be described withreference to the diagram of FIG. 3.

Step 201: A faulty link detection apparatus delivers a statisticsenabling instruction to all nodes in a unified manner, so that each nodeparticipating in monitoring performs statistical counting starting froma unified PCR packet.

In this embodiment, each device participating in monitoring may becalled a node in a network, a management center is a faulty linkdetection apparatus, and a PCR packet is a packet that carries a PCRvalue. The management center delivers a statistics enabling instructionin a unified manner, so that all nodes participating in monitoring havea unified reference standard to ensure accuracy of statistical data.Referring to a schematic diagram of information interaction betweennodes and a management center shown in FIG. 3, after the managementcenter delivers a statistics enabling instruction, Node A and Node Bacquire a current unified start PCR value, where it is assumed that astart value is PCR (t0), and enable statistics collection to performcounting starting from the current PCR value.

Step 202: All the nodes report statistical data to the management centeronce every fixed quantity of PCR packets.

In this embodiment, a time interval for all the nodes to reportstatistical data is preset according to a requirement. To ensure theunity and accuracy of time, an interval of the preset quantity of PCRpackets is used as a reference standard. An interval of the quantity ofPCR packets is represented by ΔPCR, and ΔPCR=n PCR packets, where n maybe 100, 150 and so on, which is not specifically limited in thisembodiment.

In this embodiment, all the nodes report statistical data to themanagement center once every preset quantity of PCR packets, where thestatistical data includes a start PCR value and an end PCR value, andthe quantity of packets received at the start PCR value and the quantityof packets received at the end PCR value. Referring to FIG. 3, Node Aand Node B feed back the quantity of received packets to the managementcenter once at an interval of ΔPCR, and collect start/end PCR values.For example, for a PCR of Node A, a start PCR value is (0), and thequantity of packets received at the start PCR value is Num (t1, A); anend PCR value is (t2), and the quantity of packets received at the endPCR value is Num (t2, A); for a PCR of Node B, a start PCR value is (0),and the quantity of packets received at the start PCR value is Num (t1,B); and an end PCR value is (t3), and the quantity of packets receivedat the end PCR value is Num (t3, B).

Step 203: The management center determines whether end PCR values in thestatistical data reported by all the nodes are consistent. If the endPCR values are consistent, perform step 205; and otherwise, perform step204.

If a PCR packet carrying a PCR value is lost, a problem that end PCRvalues are inconsistent occurs when the quantity of PCRs at a presetinterval is counted. In this embodiment, the management center keeps thestatistical data for a certain period of time and checks whether end PCRvalues in packets that carry PCRs and are reported by monitoring nodesare consistent, and if the end PCR values are consistent, comparesstatistical counts of received packets of different nodes, and analyzesthe quantity of packets lost between which PCR values of which device.If it is found that an end PCR value that is carried in statisticalcounts reported by a certain node is greater than end PCR values ofother nodes, it indicates that the node may lose a PCR packet; and atthis time, the management center sends a message to the node forcorrecting its ΔPCR.

Step 204: The management center corrects an end PCR value of a nodeuntil the end PCR values reported by all the nodes are consistent, wherethe end PCR value of the node is inconsistent with end PCR values ofother nodes.

In this embodiment, if received end PCR values are inconsistent, a PCRvalue received by the monitoring node is corrected first until end PCRvalues are the same in statistical data reported by monitoring nodes.Referring to FIG. 3, if the management center finds that the PCR (t2)and the PCR (t3) are inconsistent, the management center sends acorrection message to a node whose end PCR value is inconsistent withthose of other nodes to correct its ΔPCR. The node receiving thecorrection message modifies the quantity of collected PCR packets, sothat when collecting statistical data again, the node whose end PCRvalue is inconsistent with those of other nodes collects statistics atan interval of the modified quantity of packets, and reports statisticaldata, for example, a corrected end PCR value is PCR (t4), and the valueand the quantity of packets received at the value are reported to themanagement center.

If the end PCR value of Node A is inconsistent with end PCR values ofother nodes, a correction message is sent to Node A; and if the end PCRvalue of Node B is inconsistent with end PCR values of other nodes, acorrection message is sent to Node B. For example, if the presetquantity of PCR packets, which is used as an interval, is 100 and astart PCR value is 1, an end PCR value should be 100. However, the endPCR value of Node A is 101 and end PCR values of other nodes are 100, itindicates that Node A has lost one PCR packet. Then, the managementcenter delivers a correction message to Node A, so that Node A modifiesthe quantity of PCR packets, where the modified quantity of PCR packetsis used as a next interval.

Each time the management center sends a correction message, a nodesubtracts, according to the correction message, a numerical value fromthe preset quantity of PCR packets to obtain the quantity of PCRpackets, where the quantity of PCR packets is used as an interval. Then,the quantity of PCR packets obtained by Node A as a next interval is 99.In this way, the start PCR value that is sent by Node A and received bythe management center again is 102, and the end value should be 200,thereby ensuring that received end PCR values sent by all monitoringdevices are the same. An objective is to ensure the same start PCR valueand the same end PCR value for the quantity of packets participating instatistics collection, ensure clock synchronization, and avoidinaccuracy of a packet statistical result due to clock inconsistency andavoid final inaccuracy of a link in fault detection.

In this embodiment, after statistical counts are reported according to anew ΔPCR, a device automatically restores the preset quantity of PCRpackets (ΔPCR). For example, a value of the new ΔPCR is 99; and then,after end PCR values of all the nodes are modified to be consistent, themonitoring device automatically restores the ΔPCR value to 100.

In this embodiment, if an end PCR value of a certain device is stillgreater than PCR values of other devices after the correction isperformed once, the management center continues to send a message toperform correction, until end PCR values in data reported by statisticsnodes are the same. In this embodiment, steps 203 to 204 are optional,which further ensure accuracy of the quantity of lost packets. If it canbe ensured that a PCR packet is not lost, accuracy of an end PCR valuemay also not be checked.

Step 205: The management center obtains the quantity of packets lostbetween nodes according to statistical data reported at a unified ΔPCR.

In this embodiment, the management center first calculates thequantities of packets that are received by all the nodes between thesame start PCR value and the same end PCR value. A specific calculationmethod is: subtracting the quantity of packets received at the start PCRvalue from the quantity of packets received at the end PCR value, so asto obtain the quantity of packets received between the same start PCRvalue and the same end PCR value. After the quantities of packets thatare received by all the nodes between the same start PCR value and thesame end PCR value are obtained, the quantity of packets lost between anupstream device and a downstream device among all nodes participating inmonitoring is calculated.

A specific calculation method can now be described. In the same PCRinterval, subtracting the quantity of packets received by the downstreamnode from the quantity of packets received by the upstream node, so asto obtain the quantity of packets lost between the upstream device andthe downstream device. For example, the same start PCR value is PCR (t1)and the same end PCR value is PCR (t4) in FIG. 3; and then, the quantityof packets received between PCR (t1) and PCR (t4) is calculated.

Specific calculation steps are as follows:

(1) assume PCR (t1) is a time point for statistics collection, and thetotal quantities of packets received by Node A and Node B are: Num (t1,A), and Num (t1, B) respectively;

(2) assume PCR (t4) is a next time point for statistics collection, andthe total quantities of packets received by Node A and Node B are: Num(t4, A) and Num (t4, B) respectively; and

(3) the quantity of packets lost in a network between Node A and Node Band between PCR (t1) and PCR (t4) is: Diff=Num (t4, A)−Num (t1, A)−[Num(t4, B)−Num (t1, B)].

Optionally, after the quantities of packets that are received by all thenodes between the same start PCR value and the same end PCR value arecalculated, whether the quantities of packets received by the nodeswithin ΔPCR are consistent may be determined first. If the quantitiesare consistent, it indicates that there is no faulty link; and if thequantities are inconsistent, the quantity of packets lost between anupstream device and a downstream device among all devices participatingin monitoring is calculated according to the quantities of packets thatare received by all the nodes between the same start PCR value and thesame end PCR value, so as to determine a faulty link.

Step 206: Determine a faulty link according to the quantity of packetslost between an upstream node and a downstream node.

In this embodiment, the management center collects statistics, accordingto a consistent end PCR value, on the quantity of packets respectivelyreceived by each node between a previous consistent start PCR value andthe consistent end PCR value. In the case of no packet loss, the countsof packets received by different nodes in each reporting period shouldbe consistent, that is, the quantity of packets lost between an upstreammonitoring device and a downstream monitoring device is zero. Ifinconsistency is found, the management center needs to performcomparison, and obtain, through further calculation and analysis, thequantity of packets lost between devices and a device that loses apacket, where whether the quantity of packets lost between the upstreamnode and the downstream node is zero is determined, and if the quantityis not zero, it indicates that the link is a faulty link. For example,three nodes from an upstream node to a downstream node are A, B, and Crespectively, and statistical counts reported in a certain period are1000, 998, and 900 respectively; and then, the management centerobtains, through comparison, that 2 packets are lost between A and B,and 8 packets are lost between B and C. It indicates that packet lossexists both between A and B and between B and C, and a link between Aand B and a link between B and C are both faulty links.

In this embodiment, the management center finally provides a client withnodes between which a faulty link exists. If a problem occurs betweennodes A and B, nodes A and B are provided for the client, so that theclient can find the faulty link in time, and take certain measures tofinally ensure video quality for a user side.

Beneficial effects of the technical solution provided in this embodimentof the present disclosure are as follows. A monitoring management centeracquires statistical data collected at a unified reference time bydifferent network nodes, and obtains, through comparison, the accuratequantity of packets lost between an upstream node and a downstream node,thereby ensuring that an IPTV service operator locates a network faultquickly and effectively, assisting an operation and maintenance engineerin quickly removing a fault, and improving the quality of operation andmaintenance as well as service of an IPTV network.

Referring to FIG. 4, a third embodiment (Embodiment 3) of the presentdisclosure provides a faulty link detection apparatus. This embodimentincludes a receiving module 301, an acquiring module 302, and adetermining module 303.

The receiving module 301 is configured to receive statistical data thatis reported by all nodes every preset quantity of packets that carry aprogram clock reference value, where all the nodes collect statisticaldata starting from a unified program clock reference value, and thestatistical data includes a start program clock reference value and anend program clock reference value, and the quantity of packets receivedat the start program clock reference value and the quantity of packetsreceived at the end program clock reference value.

The acquiring module 302 is configured to acquire, according to thestatistical data, the quantity of packets lost between an upstream nodeand a downstream node among all the nodes.

The determining module 303 is configured to determine a faulty linkaccording to the quantity of packets lost between the upstream node andthe downstream node.

FIG. 5 illustrates a more specific example. In this embodiment, theacquiring module 302 includes a first calculating unit 302 a, configuredto calculate, according to the quantity of packets received at the startprogram clock reference value and the quantity of packets received atthe end program clock reference value, the quantities of packets thatare received by all the nodes between the same start program clockreference value and the same end program clock reference value, and asecond calculating unit 302 b, configured to calculate, according to thequantities of packets that are received by all the nodes between thesame start program clock reference value and the same end program clockreference value, the quantity of packets lost between the upstream nodeand the downstream node among all the nodes.

The determining module 303 is specifically configured to determinewhether the quantity of packets lost between the upstream node and thedownstream node among all the nodes is zero, and if the quantity is notzero, determine that a link between the upstream node and the downstreamnode is the faulty link.

Referring to FIG. 5, in this embodiment, the acquiring module 302further includes a determining unit 302 c, configured to determine,before the first calculating unit calculates the quantities of packetsthat are received by all the nodes between the same start program clockreference value and the same end program clock reference value, whetherend program clock reference values reported by all the nodes areconsistent, if the end program clock reference values are consistent,continue to perform the step of calculating the quantities of packetsthat are received by all the nodes between the same start program clockreference value and the same end program clock reference value, and ifthe end program clock reference values are inconsistent, correct an endprogram clock reference value of a node until the end program clockreference values reported by all the nodes are consistent, where the endprogram clock reference value of the node is inconsistent with endprogram clock reference values of other nodes, and continue to performthe step of calculating the quantities of packets that are received byall the nodes between the same start program clock reference value andthe same end program clock reference value.

The correcting the end program clock reference value of the node, wherethe end program clock reference value of the node is inconsistent withthe end program clock reference values of the other nodes, includessending a correction message to the node whose end program clockreference value is inconsistent with those of the other nodes, so thatthe node whose end program clock reference value is inconsistent withthose of the other nodes modifies the quantity of packets that carry aprogram clock reference value, where the quantity of packets that carrya program clock reference value is used as its own interval, andcollects statistical data at an interval of the modified quantity ofpackets that carry a program clock reference value.

FIG. 6 illustrates an embodiment of the present disclosure that providesa node, which includes a first receiving module 401, a statistics module402, and a sending module 403.

The first receiving module 401 is configured to receive an enablinginstruction delivered by a link fault detection apparatus and acquire acurrent program clock reference value.

The statistics module 402 is configured to collect statistical datastarting from the current program clock reference value.

The sending module 403 is configured to send the statistical data to thelink fault detection apparatus every preset quantity of packets thatcarry a program clock reference value, so that the link fault detectionapparatus analyzes the statistical data to determine a faulty link,where the statistical data includes a start program clock referencevalue and an end program clock reference value, and the quantity ofpackets received at the start program clock reference value and thequantity of packets received at the end program clock reference value.

In the embodiment of FIG. 7, the node further includes a secondreceiving module 404, a correcting module 405 and restoration module406. The second receiving module 404 is configured to receive acorrection message sent by the link fault detection apparatus, when thelink fault detection apparatus determines that an end program clockreference value sent by the sending module is inconsistent with endprogram clock reference values sent by other nodes.

The correcting module 405 is configured to correct, according to thereceived correction message, the quantity of packets that carry aprogram clock reference value, where the quantity of packets that carrya program clock reference value is used as its own interval, so as toobtain the new quantity of packets that carry a program clock referencevalue, where the new quantity of packets that carry a program clockreference value is used as an interval, and collect statistical dataagain, until the end program clock reference value reported by the nodeis consistent with the end program clock reference values of the othernodes.

The restoration module 406 is configured to, after statistical countingand reporting are performed at an interval of the new quantity ofpackets that carry a program clock reference value, restore the quantityof packets that carry a program clock reference value to the presetquantity of packets that carry a program clock reference value, wherethe quantity of packets that carry a program clock reference value isused as an interval.

Referring to FIG. 8, an embodiment of the present disclosure furtherprovides a faulty link detection system, including a link faultdetection apparatus 501 and a node 502.

The link fault detection apparatus 501 is configured to receivestatistical data that is reported by all nodes every preset quantity ofpackets that carry a program clock reference value, where all the nodescollect statistical data starting from a unified program clock referencevalue, and the statistical data includes a start program clock referencevalue and an end program clock reference value, and the quantity ofpackets received at the start program clock reference value and thequantity of packets received at the end program clock reference value;acquire, according to the statistical data, the quantity of packets lostbetween an upstream node and a downstream node among all the nodes; anddetermine a faulty link according to the quantity of packets lostbetween the upstream node and the downstream node.

The node 502 is configured to receive an enabling instruction deliveredby the link fault detection apparatus and acquire a current programclock reference value; collect statistical data starting from thecurrent program clock reference value; and send the statistical data tothe link fault detection apparatus every preset quantity of packets thatcarry a program clock reference value, so that the link fault detectionapparatus analyzes the statistical data to determine the faulty link.

Beneficial effects of the technical solution provided in this embodimentof the present disclosure are as follows. A faulty link detectionapparatus acquires statistical data collected at a unified referencetime by different network nodes, and obtains, through comparison, theaccurate quantity of packets lost between an upstream node and adownstream node, thereby ensuring that an IPTV service operator locatesa network fault quickly and effectively, assisting an operation andmaintenance engineer in quickly removing a fault, and improving thequality of operation and maintenance as well as service of an IPTVnetwork.

The apparatus, node, and system provided in this embodiment mayspecifically belong to the same concept as the method embodiments. Fordetails about specific implementation processes, reference is made tothe method embodiments, and the details are not described herein again.

All or part of the foregoing technical solutions provided in theembodiments of the present disclosure may be implemented by a programinstructing relevant hardware. The program may be stored in a readablestorage medium, and the storage medium may include any medium that iscapable of storing program codes, such as a ROM, a RAM, a magnetic disk,or an optical disk.

The foregoing descriptions are merely exemplary embodiments of thepresent disclosure, but are not intended to limit the presentdisclosure. Any modification, equivalent replacement, or improvementmade without departing from the spirit and principle of the presentdisclosure shall all fall within the protection scope of the presentdisclosure.

What is claimed is:
 1. A faulty link detection method, comprising:receiving statistical data that is reported by all of a plurality ofnodes for every preset quantity of packets that carry a program clockreference value, wherein the nodes collect statistical data startingfrom a unified program clock reference value and the statistical datacomprises a start program clock reference value, an end program clockreference value, a quantity of packets received at the start programclock reference value and a quantity of packets received at the endprogram clock reference value; acquiring, according to the statisticaldata, the quantity of packets lost between an upstream node and adownstream node among all the nodes; and determining a faulty linkaccording to the quantity of packets lost between the upstream node andthe downstream node.
 2. The method according to claim 1, whereinacquiring the quantity of packets lost comprises: calculating, accordingto the quantity of packets received at the start program clock referencevalue, the quantity of packets received at the end program clockreference value, the quantities of packets that are received by all thenodes between the same start program clock reference value and the sameend program clock reference value; and calculating, according to thequantities of packets that are received by all the nodes between thesame start program clock reference value and the same end program clockreference value, the quantity of packets lost between the upstream nodeand the downstream node among all the nodes.
 3. The method according toclaim 2, wherein, before calculating the quantities of packets that arereceived by all the nodes between the same start program clock referencevalue and the same end program clock reference value, the method furthercomprises: determining whether or not end program clock reference valuesreported by all the nodes are consistent; if the end program clockreference values are consistent, continuing to perform the step ofcalculating the quantities of packets that are received by all the nodesbetween the same start program clock reference value and the same endprogram clock reference value; and if the end program clock referencevalues are not consistent, correcting an end program clock referencevalue of a node until the end program clock reference values reported byall the nodes are consistent, wherein the end program clock referencevalue of the node is inconsistent with end program clock referencevalues of other nodes, and continuing to perform the step of calculatingthe quantities of packets that are received by all the nodes between thesame start program clock reference value and the same end program clockreference value.
 4. The method according to claim 3, wherein correctingthe end program clock reference value of the node comprises sending acorrection message to the node whose end program clock reference valueis inconsistent with those of the other nodes, so that the node whoseend program clock reference value is inconsistent with those of theother nodes modifies the quantity of packets that carry a program clockreference value and collects statistical data at an interval of themodified quantity of packets that carry a program clock reference value,wherein the quantity of packets that carry a program clock referencevalue is used as its own interval.
 5. The method according to claim 1,wherein determining the faulty link comprises: determining whether thequantity of packets lost between the upstream node and the downstreamnode among all the nodes is zero; and if the quantity is not zero,determining that a link between the upstream node and the downstreamnode is the faulty link.
 6. The method according to claim 1, wherein thenodes are part of an Internet Protocol television system.
 7. A faultylink detection apparatus, comprising: a receiving module, configured toreceive statistical data that is reported by all nodes every presetquantity of packets that carry a program clock reference value, whereinall the nodes collect statistical data starting from a unified programclock reference value and the statistical data comprises a start programclock reference value, an end program clock reference value, thequantity of packets received at the start program clock reference value,and the quantity of packets received at the end program clock referencevalue; an acquiring module, configured to acquire, according to thestatistical data, the quantity of packets lost between an upstream nodeand a downstream node among all the nodes; and a determining module,configured to determine a faulty link according to the quantity ofpackets lost between the upstream node and the downstream node.
 8. Theapparatus according to claim 7, wherein the acquiring module comprises:a first calculating unit, configured to calculate the quantities ofpackets that are received by all the nodes between the same startprogram clock reference value and the same end program clock referencevalue according to the quantity of packets received at the start programclock reference value and the quantity of packets received at the endprogram clock reference value; and a second calculating unit, configuredto calculate the quantity of packets lost between the upstream node andthe downstream node among all the nodes according to the quantities ofpackets that are received by all the nodes between the same startprogram clock reference value and the same end program clock referencevalue.
 9. The apparatus according to claim 8, wherein the acquiringmodule further comprises a determining unit, configured to: before thefirst calculating unit calculates the quantities of packets that arereceived by all the nodes between the same start program clock referencevalue and the same end program clock reference value, determine whetheror not end program clock reference values reported by all the nodes areconsistent; if the end program clock reference values are consistent,continue to perform the step of calculating the quantities of packetsthat are received by all the nodes between the same start program clockreference value and the same end program clock reference value; and ifthe end program clock reference values are not consistent, correct anend program clock reference value of a node until the end program clockreference values reported by all the nodes are consistent, wherein theend program clock reference value of the node is inconsistent with endprogram clock reference values of other nodes, and continue to performthe step of calculating the quantities of packets that are received byall the nodes between the same start program clock reference value andthe same end program clock reference value.
 10. The apparatus accordingto claim 9, wherein the determining unit is configured to correct theend program clock reference value of the node by sending a correctionmessage to the node whose end program clock reference value isinconsistent with those of the other nodes, so that the node whose endprogram clock reference value is inconsistent with those of the othernodes modifies the quantity of packets that carry a program clockreference value, wherein the quantity of packets that carry a programclock reference value is used as its own interval, and collectingstatistical data at an interval of the modified quantity of packets thatcarry a program clock reference value.
 11. The apparatus according toclaim 7, wherein the determining module is specifically configured to:determine whether the quantity of packets lost between the upstream nodeand the downstream node among all the nodes is zero; and if the quantityis not zero, determining that a link between the upstream node and thedownstream node is the faulty link.
 12. The apparatus according to claim7, wherein the apparatus is part of an Internet Protocol televisionsystem.
 13. A node, comprising: a first receiving module, configured toreceive an enabling instruction delivered by a link fault detectionapparatus and acquire a current program clock reference value; astatistics module, configured to collect statistical data starting fromthe current program clock reference value; and a sending module,configured to send the statistical data to the link fault detectionapparatus every preset quantity of packets that carry a program clockreference value, so that the link fault detection apparatus analyzes thestatistical data to determine a faulty link, wherein the statisticaldata comprises a start program clock reference value, an end programclock reference value, a quantity of packets received at the startprogram clock reference value and a quantity of packets received at theend program clock reference value.
 14. The node according to claim 13,further comprising: a second receiving module, configured to receive acorrection message sent by the link fault detection apparatus, when thelink fault detection apparatus determines that the end program clockreference value sent by the sending module is inconsistent with endprogram clock reference values sent by other nodes; a correcting module,configured to correct, according to the received correction message, thequantity of packets that carry a program clock reference value, whereinthe quantity of packets that carry a program clock reference value isused as its own interval, so as to obtain the new quantity of packetsthat carry a program clock reference value, wherein the new quantity ofpackets that carry a program clock reference value is used as aninterval, and collect statistical data again, until the end programclock reference value reported by the node is consistent with the endprogram clock reference values of the other nodes; and a restorationmodule, configured to, after statistical counting and reporting areperformed at an interval of the new quantity of packets that carry aprogram clock reference value, restore the quantity of packets thatcarry a program clock reference value to the preset quantity of packetsthat carry a program clock reference value, wherein the quantity ofpackets that carry a program clock reference value is used as aninterval.
 15. The node according to claim 13, wherein the node is partof an Internet Protocol television system.
 16. A faulty link detectionsystem, comprising: a link fault detection apparatus, configured toreceive statistical data that is reported by all nodes every presetquantity of packets that carry a program clock reference value, whereinall the nodes collect statistical data starting from a unified programclock reference value, and the statistical data comprises a startprogram clock reference value, an end program clock reference value, aquantity of packets received at the start program clock reference valueand a quantity of packets received at the end program clock referencevalue; to acquire, according to the statistical data, the quantity ofpackets lost between an upstream node and a downstream node among allthe nodes; and to determine a faulty link according to the quantity ofpackets lost between the upstream node and the downstream node; and anode, configured to receive an enabling instruction delivered by thelink fault detection apparatus and acquire a current program clockreference value; to collect statistical data starting from the currentprogram clock reference value; and to send the statistical data to thelink fault detection apparatus every preset quantity of packets thatcarry a program clock reference value, so that the link fault detectionapparatus analyzes the statistical data to determine the faulty link.